![]() ![]() What happens when a switch does not have room to store a new MAC address? And what happens if an entry that was there 2 seconds ago was just overwritten by another entry?įorced Flooding MAC Flooding Attacks Host C starts running macof. High-end LAN switches can store hundreds of thousands of entries, while entry-level products peak at a few hundred.įorcing an Excessive Flooding Condition MAC Flooding Attacks If a switch does not have an entry pointing to a destination MAC address, it floods the frame. This information is crucial to a LAN hacker. Because each entry occupies a certain amount of memory, it is practically impossible to design a switch with infinite capacity. MAC Flooding Attacks Virtually all LAN switches on the market come with a finite-size bridging table. Values for any options left unspecified will be generated randomly.īecause macoff generates random MAC addresses it sometimes generates MAC addresses that are not valid (in which case those packets will be dropped).Defeating a Learning Bridge’s Forwarding Process Exploiting the Bridging Table: MAC Flooding Attacks MAC Flooding Alternative: MAC Spoofing Attacks A straight C port of the original Perl Net::RawIP macof program by Ian Vitek -i interface Macof floods the local network with random MAC addresses (causing some switches to fail open in repeating mode, facilitating sniffing). Why? Because if the shared table is full than each VLAN no longer knows what ports legitimate MAC address(es) are on. Flooding a single VLAN would force all other VLANs to flood as well (just flood their own VLAN). Most switches today do not have separate tables for each VLAN. Why is this helpful? Broadcast packets will only occur within the same VLAN (Even they are on the same switch). ![]() ![]() You can group a number of ports on a switch together and say they are part of a VLAN (they are logically separated from other VLANs). What is the point of filling up switches table with fake make addresses? It forces the switch to become a hub (and you as an attacker can now see traffic on every port as all packets are now broadcasted) However many other switches will let their entire table get filled up with fake addresses! This is beneficial to you if you wish to receive traffic intended for other people! If you fill up a switches table with random mac addresses different vendors switches will behave differently.Ĭisco switches will keep original MAC address on its table and will only remove them if they time out. Today’s Lesson is on flooding a network with random MAC addresses. Before you can be a badass hacker you need to understand what exactly it is your doing. ![]()
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